WO2010103098A1

WO2010103098A1 - Device and method for the nondestructive monitoring of complex structures using ultrasonic waves

Info

Publication number: WO2010103098A1
Application number: PCT/EP2010/053172
Authority: WO
Inventors: Guillaume Ithurralde
Original assignee: European Aeronautic Defence And Space Company Eads France
Priority date: 2009-03-12
Filing date: 2010-03-12
Publication date: 2010-09-16
Also published as: EP2406625B1; FR2943136B1; FR2943136A1; EP2406625A1

Abstract

The invention relates to a device (1) for the nondestructive monitoring of a complex structure (5) using ultrasonic waves, comprising an ultrasonic probe comprising a matrix array of basic transducers (200a, 200b) that can be configured according to a plurality of different activation modes, a monitoring head (2) to which the probe (20) is attached, and an automaton (3) having the monitoring head (2). The device (1) also includes a plurality of end elements (22), each end element comprising a surface geometrically adapted to an area of the structure (5), means for selecting an end element (22) from the plurality of end elements and an activation mode from the plurality of activation modes, means for controlling an attachment, by the automaton (3), of the selected end element (22) to the monitoring head (2), and means for configuring the probe (20) with the selected activation mode. The invention also relates to a method for the nondestructive control of complex structures using ultrasonic waves.

Description

Device and method for non-destructive ultrasonic testing of complex structures

The present invention belongs to the field of ultrasonic non-destructive testing of structures, and more particularly relates to a device and a method for non-destructive ultrasonic testing of a complex structure in local or total immersion in a liquid coupling medium, such as only water.

Nowadays, the non-destructive testing methods, especially ultrasonic, are implemented in many industrial fields such as the fields of aeronautics, nuclear, naval, etc.

The methods of non-destructive ultrasonic testing generally involve emitting ultrasound waves by means of a probe towards a structure, and measuring characteristics of said ultrasonic waves, either after reflection by the structure or after transmission through the structure.

In the case where the probe is not supported on the structure, the non-destructive control methods require a profile follow-up of the structure to be controlled. Profile tracking is necessary, for example, to maintain an angle of incidence of the ultrasonic waves on the substantially constant structure, and / or to limit the leakage of coupling liquid in the case of a local immersion control of the structure.

Nowadays, more and more complex structures are appearing, and make the profile tracking complicated. For example, it is not uncommon for an aircraft wing or fuselage structure to have different geometries depending on the zone in question, geometries that are dictated by the function of the structure (curvature, broken plane, etc.) or due to the presence of built-in functions in the structure (stiffener, dropped edges, etc.). It is not uncommon to have a different thickness depending on the area.

In practice, it is necessary to control such structures to consider a plurality of ultrasonic probes of different characteristics, each probe being specialized for a specific area of the structure.

Profile tracking and probe changes tend to increase the duration of non-destructive testing of complex structures, and production rates are therefore penalized.

The present invention proposes to solve the aforementioned problems by means of a device and a method of non-destructive ultrasonic testing adapted to the automated control of such structures. The invention relates to an ultrasonic non-destructive testing device of a structure having a plurality of different geomete areas. The device comprises an ultrasonic probe, a control head to which the probe is attached, and an automaton carrying the control head.

According to the invention, the probe comprises a matrix array of elementary transducers that can be configured according to a plurality of different activation modes, and the device comprises:

a plurality of terminal elements, each terminal element comprising a fixing interface common to all the terminal elements and a surface of its own, geometrically adapted to a zone of the structure,

means for selecting a terminal element from the plurality of terminal elements and means for selecting an activation mode from among the plurality of activation modes as a function of a geometry of a zone of the structure means for controlling a fixing by the PLC of the selected terminal element to the control head, and means for configuring the probe with the selected activation mode.

Preferably, the device comprises information storage means associating a terminal element and an activation mode to each zone to be controlled. Preferably, the information associates a zone of standard geometry with each zone to be controlled of the structure.

Preferably, the clean surface of each terminal element comprises a deformable pad.

Advantageously, the device comprises a plurality of sets of different terminal elements, each set being adapted to particular control conditions.

The invention also relates to a method of non-destructive ultrasonic testing which comprises the steps of: a) selection of a control zone of the structure, b) selection of a terminal element and selection of a mode of activation of the probe according to a geometry of the zone to be checked, c) fixation of the terminal element selected at the control head and configuration of the probe according to the selected activation mode, d) positioning of the control head in the vicinity of the area to be controlled and ultrasonic inspection of said zone.

Steps a), b), c) and d) are preferably repeated for each area to be controlled of the structure.

In a variant, during step a), a set of controllable zones with the same terminal element is selected, during step b) a terminal element is selected according to the geometheses of the set, and step d) is executed with the same end element for all areas of the set.

Preferably, the method comprises a preliminary step of determining information associating a terminal element and an activation mode with each zone to be controlled of the structure.

The following description of embodiments of the invention is made with reference to the figures, which show in a nonlimiting manner:

FIG. 1: a schematic representation of a non-destructive ultrasonic testing device according to the invention,

FIGS. 2a to 2e: schematic representations in section of contact control heads according to the invention, FIGS. 3a and 3b: schematic cross-sectional representations of non-contact control heads according to the invention,

FIG. 4 is a diagrammatic representation of an example of an array of elementary transducers of an ultrasound probe of the device of FIG. 1. The preferred field of application of the invention, although in no way limiting, is that of non-limiting control. destructive structures implemented in aeronautics, in particular structures of laminated composite material of the type comprising fibers held by a thermosetting resin or high-performance thermoplastics, or metal structures (steel, titanium, aluminum, etc.).

The present invention relates to a non-destructive ultrasonic control by liquid coupling. In a manner known to those skilled in the art, such a liquid coupling is obtained by total or partial immersion of a structure in a vessel containing the liquid coupling, preferably water, or by local immersion of the structure. by continuous supply of the liquid coupling between an ultrasonic probe and the structure to be tested (water boxes, water jets, etc.).

We consider in the following the case of a control of a structure 5, called "complex", comprising a plurality of areas to be controlled not all of the same geometry.

"Geometry" is here to understand in the broad sense, that is to say not only the geometry of a local surface of a front face of a zone, the front face being the face of the side of a probe emitting ultrasonic waves towards the structure 5, but also the thickness of the zone, the local inclination between the front face and a rear face of the zone, etc.

An example of a device 1 for non-destructive ultrasonic testing according to the invention, adapted to a reflection control, is shown diagrammatically in FIG. 1. According to the invention, the device 1 for non-destructive ultrasonic testing comprises a control head 2, an automaton 3 for moving the control head 2, and a control unit 4 for controlling the operation of said device.

During the control operations, the control head 2 is either supported on the structure 5 and the control is said "in contact" or without support on the structure 5 and the control is said "contactless".

The control head 2 mainly comprises an ultrasonic probe 20 mounted on a support 21 and a removable terminal element 22. The terminal element 22 is fixed to the support 21 by means adapted for assembly / disassembly by the controller 3 without intervention of an operator.

The terminal element 22 has a first end 220 and a second end 221, opposite the first end and fixed to the support 21 during the control operations of the structure 5. The second end 221 cooperates with the support 21 in which it fits. According to other non-limiting embodiments, the fixing is carried out by means of electromagnets (for example arranged on the support 21 and / or on the terminal element 22), by screwing, by bayonet, etc. Preferably, the dimensions of the terminal element 22 are chosen to ensure that the ultrasonic waves emitted by the probe 20 travel a predefined distance before being reflected by the area to be controlled. For example, the height of the terminal element 22, measured between the first end 220 and the second end 221, is chosen so that the round trip delay of the ultrasonic waves in the coupling liquid is greater than the propagation time / return of ultrasonic waves in structure 5.

The first end 220 of the terminal element 22 forms a surface geometrically adapted to a local surface of a zone to be controlled, that is to say that the surface formed by the first end 220 and the local surface locally have substantially the same surface. same geometry, to ensure the profile of the structure 5 monitoring by the control head 2, the control is performed in contact or without contact.

For the purposes of describing embodiments of the terminal element 22, the nonlimiting case of a local immersion contact control is first considered.

In the case of a contact control, the surface formed by the first end 220 is called "bearing surface" because it is intended to bear and slide on the local surface of the area to be controlled. structure 5. The terminal element 22 is also intended to cause the necessary incidence of the ultrasonic wave beam emitted by the probe 20 on the local surface of the zone to be controlled, preferably a substantially normal incidence in the case of composite materials laminates.

FIGS. 2a to 2e schematically represent nonlimiting examples of end elements 22 of the non-destructive testing device 1.

FIG. 2a shows a terminal element 22 geometrically adapted to a zone comprising a substantially flat local surface.

Figures 2b and 2c show terminal elements 22 geometrically adapted to areas having a respective convex (omega stiffener base) and concave local surface.

Figure 2d shows a terminal element 22 geometrically adapted to an edge zone locally having a front face and a substantially planar edge, orthogonal to each other.

FIG. 2e shows a terminal element 22 geometrically adapted to an area comprising a T-shaped stiffener, said terminal element comprising an internal mirror 224 to ensure a substantially normal incidence of the ultrasonic waves on the transverse walls of said stiffener. In a preferred embodiment, the terminal element 22 has a perimeter wall between the first 220 and second 221 ends.

When the terminal element 22 is fixed to the support 21 and when the control head 2 bears on the local surface of the structure 5 with which the support surface is geometrically adapted, the terminal element 22, the support 21, the probe 20 and the structure 5 delimit a substantially closed coupling chamber 23. The coupling chamber 23 has openings 24 which are used for the continuous filling of the coupling chamber 23 with coupling liquid.

Preferably, the bearing surface of the first end 220 comprises a deformable pad 222, such as a perimeter seal, to facilitate the sliding of the control head 2 on the structure 5 and to limit the losses of coupling liquid.

In a preferred embodiment, the coupling chamber 23 comprises a transverse membrane vis-à-vis the probe 20, delimiting a first coupling chamber, on the side of said probe, and a second coupling chamber on the other side. the structure 5, of volume preferably substantially lower than that of the first coupling chamber.

The membrane 25 is impermeable to the coupling liquid and is substantially transparent in the ultrasound range. This is for example a latex sheet of thickness between 0.1 mm and 0.2 mm and acoustic impedance close to that of the coupling liquid. This mode is advantageous because only the filling of the second coupling chamber in liquid coupling must be carried out continuously during the operations of control, the first coupling chamber being preferably filled at the beginning of the control operations.

More generally, the contention of the coupling liquid, that is to say the fact that the coupling chamber 23 must be essentially closed, corresponds to the case of local immersion. According to other embodiments, which can be implemented for total or partial immersion contact control, the terminal element 22 comprises a semi-perimetrical wall, for example a U-shaped wall, or comprises at least two prominent parts. providing points of support on the structure 5, etc. Even more generally, the terminal elements 22 are according to other embodiments adapted to a non-contact control, for example by water jet. Examples of such end elements are visible in Figures 3a and 3b, for a local surface respectively flat and concave. The first end 220 is preferably nozzle-shaped and comprises a skirt 223 flexible or semi-rigid geometrically adapted to the local surface of the area to be controlled. During the control operations, the skirt 223 is kept substantially parallel to said local surface to limit water leakage and provide acoustic coupling.

According to the invention, the non-destructive testing device 1 comprises a plurality of interchangeable terminal elements 22, geometrically adapted to different zones of the structure 5. The terminal elements 22 are for example arranged on a desk 30 accessible by the PLC 3 carrying the control head 2. Each terminal element 22 has an interface common to all the terminal elements, formed by the second end 221, intended to cooperate with the support 21.

Preferably, the device 1 comprises a plurality of sets of end elements 22, each set being adapted to particular conditions of control. For example the device 1 comprises a game for a contactless control, a game for contact control in local immersion, total immersion, etc.

Due to this plurality of interchangeable end elements 22, which can be mounted / dismounted on the support 21 by simple operations performed by the controller 3, the non-destructive testing device 1 by ultrasound is suitable for automated control of complex structures.

The ultrasonic probe of the non-destructive testing device 1 comprises a matrix array of elementary transducers 200a, 200b, preferably made of piezoelectric material. The elementary transducers 200a, 200b are configured by means of a multi-channel electronics 201 adapted to individually activate each of said elementary transducers in transmission and / or reception. Preferably all or part of the elementary transducers can be activated both in transmission and in reception. In the nonlimiting example shown in FIG. 4, the probe 20 comprises a substantially circular, preferably substantially planar, two-dimensional network comprising three peripheral elementary transducers 200a which are activatable only in transmission, and a plurality of central elementary transducers 200b. , substantially smaller in size than the peripheral elementary transducers 200a, which are activatable both in transmission and in reception.

The multi-channel electronics 201 is adapted to configure the matrix array of elementary transducers 200a, 200b according to a plurality of different activation modes, each activation mode being defined at least by a transmitting active surface and a receiving active surface.

An active surface in emission corresponds to a set of transducers activated simultaneously in emission, and a receiving active surface corresponds to a set of transducers whose electrical signals at the output are combined with each other, for example by the multichannel electronics 201.

The multi-channel electronics 201 is preferably also adapted to perform an electronic scanning of the active surfaces in transmission and reception, that is to say to move sequentially the active surface in transmission and / or the active surface in reception within the elementary transducer array 200a, 200b. An activation mode is, if necessary, also defined by the electronic scanning of the active surfaces in transmission and reception.

Preferably, the multi-channel electronics 201 is also adapted for applying different delays to the electrical signals on each elementary transducer 200a, 200b of the same transmitting and / or receiving active surface, in order to modify the preferred direction of the ultrasonic waves or to focus the ultrasonic beam. According to other embodiments, the multi-channel electronics 201 is also adapted to weight the voltage of the electrical signals on each elementary transducer to reduce the side lobes of the emission radiation pattern and / or the gain in reception. An activation mode is, where appropriate, also defined by the applied delays and / or the weightings applied to the electrical signals on each elementary transducer of the same transmitting and / or receiving active surface.

Due to the plurality of different activation modes, it is possible to select an activation mode adapted to each area to be controlled of the structure 5, depending on the geometry of this area to be controlled, that is to say according to at least one of the following characteristics: the geometry of the local surface, the thickness of the structure 5, the local inclination between the front face and the rear face of the structure 5, etc. In addition, the adaptation of the probe 20 to the zone to be controlled is obtained quickly by configuring the multi-channel electronics 201. For example, depending on the geometry of the zone to be controlled, an activation mode is selected whose transmitting active surface and / or the delays applied to each elementary transducer 200a, 200b of said emitting active surface are configured so as to form a wavefront geometrically adapted to the local surface of the area to be controlled. In other words, the emitting active surface and / or the delays applied to each elementary transducer 200a, 200b of said emitting active surface are configured so as to have a substantially normal incidence at any point on the local surface of this zone. to control.

In the example shown in FIG. 2a, the activation mode selected is such that the ultrasonic rays emitted by the probe 20, shown in broken lines, are substantially parallel and the wavefront is substantially plane.

In the examples shown in FIGS. 2b and 2c, the mode selected activation is such that the ultrasonic rays converge at a virtual focal point F substantially coincident with a center of curvature of the local surface of the structure 5.

In the example of FIG. 2b, the point F lies between the probe 20 and the front face of the structure 5. The ultrasonic rays, after having crossed each other, diverge and form a substantially spherical wavefront centered in F geometrically adapted to the convex local surface.

In the example of Figure 2c, the point F is, relative to the probe 20, after the front face of the structure 5, and the ultrasonic beams form a wavefront geometrically adapted to the concave local surface.

In the case of a control of a structure of anisotropic material, such as a structure of laminated composite material, the device 1 is preferably configured so that the structure 5 is between 0.5 and 1.5 times the near field limit the ultrasonic beam formed by the probe 20 (or point F if a focusing delay law has been used). The activation mode is preferably selected so as to place the near-field boundary between the front and rear faces of the structure 5, and the selection of the activation mode is effected according to the thickness of said structure in the area considered. More generally, an increase in the surface area of the active surface in emission causes an increase in the directivity of the ultrasound beam emitted. Increasing the directivity maximizes the energy emitted in the preferred direction, which is advantageous especially in the case of a control of a thick and absorbent zone. Preferably, the greater the thickness of the structure in the zone considered, the greater the number of elementary transducers of the active surface in emission of the selected activation mode will be important.

Increasing the surface area of the active reception surface makes it possible, by combining the electrical signals at the output of several elementary transducers 200b, to improve a signal-to-noise ratio on reception and thus to detect smaller defects than with a single elementary transducer. 200b, and / or detect strongly attenuated ultrasonic waves in the case of a thick zone. The activation mode is for example selected as a function of the accuracy with which the defects are to be dimensioned, a precision which depends, in a manner known to those skilled in the art, on the dimensions of the active surfaces in transmission and in reception, but also laws of delay. If the speed of the control is preferred over the accuracy, an increase in the areas of the active surfaces in transmission and reception makes it possible to accelerate said control of the zone considered, because larger areas are controlled simultaneously.

The automaton 3, known in itself to those skilled in the art, is implemented to move the control head 2 in space, in order to position it in the vicinity of a zone to be controlled (in contact with or without contact), but also to replace the terminal element 22 with another terminal element to provide profile tracking of the structure 5 to be controlled.

It is thus clear that the choice of an activation mode adapted to the geometry of the area of interest of the structure 5 makes it possible to improve the performance of the control in the case of a complex structure.

In a preferred embodiment, the controller 3 comprises a robot with six articular axes carrying an effector 31 of which the control head 2 is integral. For large structures, the six-axis robot is preferably mounted on an additional linear axis or on a mobile platform.

The automaton 3 preferably comprises one or more position sensors implemented by the control unit 4 to estimate the position of the control head 2 with respect to the structure 5. The control unit 4 of the device 1 comprises control means of the controller 3, in particular displacements of the control head 2 and replacements of the terminal element 22 by said controller, and configuration means of the probe 20 via the multi-channel electronics 201. L control unit 4 also comprises means for selecting a terminal element 22 and means for selecting an activation mode according to a geometry of a zone to be controlled.

In a preferred embodiment, the control unit 4 is a PC type microcomputer, comprising a microprocessor 40, means storage devices such as an electronic memory 41, peripherals 42 such as a display screen, as well as inputs-outputs 43 coupled to the PLC 3 and the multi-channel electronics 201. The microprocessor 40, the electronic memory 41 and the inputs-outputs 43 are connected by a data bus 44.

The electronic memory 41 includes a first memory zone in which are stored instructions that are executed by the microprocessor 40 to select a terminal element 22 and an activation mode according to a geometry of a zone to be controlled, to control the setting by the controller 3 of the terminal element 22 selected at the control head 2, and to configure the probe 20 with the activation mode selected via the multichannel electronics 201.

Preferably, the selection is performed by means of information, stored in a second memory zone of the electronic memory 41, associating a terminal element 22 and an activation mode with each zone to be controlled. This information is for example stored in the form of a table of correspondences.

In another example, this information is in the form of two correspondence tables: a first table associating the zones to be checked with zones of standard geometry, and a second table associating the terminal elements 22 and the activation modes with said zones. standard geometry.

This information is preferably determined automatically by the control unit 4, for example on the basis of a CAD file describing the structure 5. According to other embodiments, this information is determined by an operator.

The invention also relates to a method of non-destructive ultrasonic testing of a structure comprising a plurality of different geomethes zones, said method being implemented by the device 1. The non-destructive control method mainly comprises the steps following: a) selection of a control zone of the structure 5, b) selection of a terminal element 22 and an activation mode adapted to the geometry of the zone in question, c) attachment of the selected end element 22 to the control head 2 and configuration of the probe 20 according to the selected activation mode, d) positioning of the control head in the vicinity the area to be controlled (contact or non-contact) and ultrasonic inspection of the area.

According to other modes of implementation, the method may comprise other steps. For example, in the case of a local immersion contact test, using the control heads 2 described with reference to FIGS. 2a to 2e, the method comprises filling the first and second coupling chambers, the first coupling chamber being filled. after step c) and before the inspection of the zone, and the second coupling chamber being filled in step d) after the positioning and before the inspection of said zone.

For the control of several zones of the structure 5, a preferred mode of implementation of the method consists in repeating the steps a), b), c) and d) for each zone to be controlled of the structure 5.

In a variant, during step a), a set of zones that can be inspected using a same terminal element 22 is determined, for example zones whose local surfaces all have substantially the same geometry.

During step b), a terminal element 22 to be used to inspect all the zones of the assembly is selected. The activation mode is preferably determined individually for each area of the set, but may be the same for all areas of the set.

Step c) is unchanged and during step d), all the zones determined to be inspected with the same end element 22 and with the selected activation mode are inspected. Steps a), b), c) and d) are repeated for each set of areas that can be inspected with the same end item 22.

The duration of the operations related to the replacement of the terminal element 22 may be significant compared to the duration of the control of the As a whole, it is understood that this mode is advantageous because the number of replacements of the terminal element is minimized.

In a particular mode of implementation, the method comprises a preliminary step in which the information combining a terminal element 22 and an activation mode is determined for each zone to be controlled. For example, for each zone to be controlled, the standard geometry zone whose geometry is closest to that of the zone to be controlled is determined, the geometry of each zone to be checked preferably being obtained from a CAD file describing the geometry of the zone to be controlled. structure 5. The invention, described in the case of a reflection control, is also applicable to a transmission control. The device 1 comprises in this case at least a first control head 2 for the emission of ultrasonic waves and a second control head 2 for the reception of ultrasonic waves, on either side of the structure 5.

Claims

1 - Device (1) for non-destructive ultrasonic testing of a structure (5) comprising a plurality of zones of different geometries, said device comprising:

an ultrasound probe (20) for emitting ultrasonic waves towards the structure (5),

a control head (2) to which the probe (20) is fixed,

an automaton (3) carrying the control head (2), characterized in that the probe (20) comprises a matrix array of elementary transducers (200a, 200b) configurable according to a plurality of different activation modes, and in that the device (1) comprises:

a plurality of terminal elements (22), each terminal element comprising a fixing interface common to all the terminal elements (22) and a surface of its own geometrically adapted to a zone of the structure (5),

means for selecting a terminal element (22) from among the plurality of terminal elements and means for selecting an activation mode from among the plurality of activation modes of the probe (20) as a function of a geometry of a zone of the structure (5),

means for controlling an attachment by the automaton (3) of the selected terminal element (22) to the control head (2),

- Configuration means of the probe (20) with the selected activation mode. 2 - Device (1) according to claim 1, comprising means (41) for storing information associating a terminal element (22) and an activation mode to each zone to be controlled.

3 - Device (1) according to claim 2, wherein the information associates a zone of standard geometry to each area to be controlled of the structure (5).

4 - Device (1) according to one of the preceding claims, wherein the clean surface of each end element comprises a pad (222) deformable.

5 - Device (1) according to one of the preceding claims, comprising a plurality of sets of end elements (22), each set being adapted to particular conditions of control. 6 - Method of non-destructive ultrasonic testing of a structure (5), implemented by the device (1) according to one of claims 1 to 5, characterized in that it comprises the steps of: a ) selection of a control zone of the structure (5), b) selection of a terminal element (22) and selection of an activation mode of the probe (20) according to a geometry of the zone to be checked, c) attachment of the selected end element (22) to the control head (2) and configuration of the probe (20) according to the selected activation mode, d) positioning of the control head (2) ) in the vicinity of the area to be checked and ultrasonic inspection of said area.

7 - Process according to claim 6, wherein the steps a), b), c) and d) are repeated for each area to be controlled of the structure (5).

8 - Process according to claim 6, wherein during step a) a set of controllable zones with a same terminal element (22) is selected, a terminal element (22) is selected during step b). depending on the geometries of the zones of the set, and the step d) is executed with the same terminal element (22) for all the zones of the set.

9 - Method according to one of claims 6 to 8, comprising a prior step of determining information associating an end element

(22) and a mode of activation of the probe (20) to each zone to be controlled of the structure (5).